With respect to the W-CDMA (Wideband Code Division Multiple Access) process according to the third generation partnership project (3GPP) which has been finding widespread usage in recent years, there has been proposed a HSDPA (High Speed Downlink Packet Access) process for realizing transmitting packets at high speeds in downlink, and research and development efforts have been made for the HSDPA process.
Research and development efforts have also been made for a multi-input multi-output (MIMO) communication process for transmitting data from a plurality of antennas of a transmitter and receiving the data with a receiver having a plurality of antennas. According to the multi-input multi-output communication process, each of the transmitter and the receiver has a plurality of antennas, and transmits or receives divided pieces of data simultaneously or parallel through the antennas for the purpose of increasing the transmission capacity, i.e., the throughput. The multi-input multi-output communication process is also applicable to a plurality of receivers each having a plurality of antennas. The multi-input multi-output communication process is considered to be a means for realizing services using the HSDPA process.
In order for a receiver having a plurality of antennas to properly receive transmitted data, there has been devised a method of measuring the reception quality of data transmitted from the transmitter and received by the receiver and performing transmission scheduling with the transmitter based on the measured reception quality (see, for example, PC(WO) No. 2004-535106).
According to the method disclosed in PC(WO) No. 2004-535106, however, transmission scheduling is performed based on only one of a plurality of reception qualities. The characteristics of the data received by the receiver tend to vary depending on which one of the plural reception qualities is used to perform transmission scheduling.
When resources to be assigned to antennas are established based on the reception quality representative of the propagation environment between a preset transmitter antenna and a preset receiver antenna, the data that are received by the receiver antenna based on which the reception quality has been measured are properly decoded. However, the data that are received by the other receiver antennas based on which the reception quality has not been measured are no properly decoded, and resources such as the number of codes and electric power are wasted for those other receiver antennas. As a result, radio wave interferences may be increased and the number of multiplex data may be reduced, the resources may not effectively be utilized, and an increased throughput, which is a feature of the multi-input multi-output communication process, may not be achieved.